Answer: d=5
Step-by-step explanation:
Arithmetic progression
An=a1+d(n-1)
An= nth term
A1= first term
D= common difference
N= nth position
We are given the 4th and 7th terms
For 4th term,n=4
A4=a1+d(4-1)
A4= 16
16= a1+d(4-1)
16= a1+3d........equation 1
For the 7th term,n=7
A7=a1+d(7-1)
A7= 31
31=a1+6d......equation 2
Bring them together
16=a1+3d
31=a1+6d
Subtract equation 1 from 2
So we have
15=3d
D=15/3
D=5
Therefore, the common difference is 5
